Power driven tool



I P 23, 1941' G. c. ROBINSON 2,256 ,496

POWER DRIVEN TOOL Filed Sept. 27, 1940 INVENTQR ATTORNEY.

Patented Sept. 23, 1941 UNITED STATES PATENT OFFICE POWER DRIVEN TOOL Girard C. Robinson, Maywood, 111.

Application September 27, 1940, Serial No. 358,633

4 Claims. (CI. 19.2-30.5)

This invention .relates to improvements in power driven tools.

In the use of power driven rotary tools for tightening nuts, bolts, or the like, or for operating drills, it is necessary to provide mechanism for preventing damage to the tool, motor, or operating parts when the nut or bolt is fully set or when resistance to turning is encountered. It is also desirable in the case of tightening a nut or bolt or the like that, when the nut or bolt is almost tight, extra power be provided to give the nut or bolt one or more final turning vi npacts.

Heretofore, various mechanisms have been proposed for accomplishing the above purpose, including cooperating clutch members and springs wherein a relative longitudinal movement takes place between the clutch members when resistance is encountered due to foreshort- Y ening action produced by a wound up spring to cause the clutch to alternately disengage and engage. These devices are complicated and expensive, and because of the heavy springs which it is necessary to use and the arrangement of the clutch members, they are capable of being properly operated only by an air motor of relatively large horsepower, because at .each impact, after a resistance is encountered, the motor stalls temporarily making it impractical to employ an electric motorbecause of the damage which results from the stalling.

It is one of the objects of the present invention to provide a tool operating unit or adaptor for the above purpose which can be properly driven by a fractional horsepower electric motor without damage to said motor, whereby garages or other small institutions having electric drills can readily use the adaptor of the present invention to convert their drills into tighteners for nuts, bolts, and the like.

A more specific object of the invention is to provide a power driven tool construction wherein there is a radial jaw for effecting driving connection with the tool and wherein an eccentric is utilized to draw said jaw radially inwardly to disengaged position when resistance is encountered, there being spring means for rotatably throwing the jaw into anew position of engagement with the weight of the jaw delivering a driving impact at said new position.

A further object of the invention is to provide a construction'for power driven tools which can be employed either as an adaptor or be built in as a permanent part of an electric or pneu-" matic tool.

A further object of the invention is to provide a power driven tool construction embodying relatively few-simple parts and which is as a result relatively inexpensive to manufacture.

eccentric construction;

Fig. 3 is a sectional view through the spindle looking inwardly at the operating parts, with the outer shell removed, showing the jaw in driving engagement;

Fig. 4 is a similar'view showing the jaw after it has been drawn radially inwardly a short distance due to rotation of theeccentric; and

Fig. 5 is a similar view showing the Jaw pulled threaded bore 9 in its outer end to facilitate connection of the spindle 8 with the spindle'of .an electric drill or any other suitable source oi-power. The spindle 8 may have flattened sides III. Ong an intermediate portion of the spindle is an annular ridge II adapted to cooperate with a similarly formed part I! at the inner end of a bore l3 formed in the neck ll of a shell ii. A set screw I6 cooperable with a depression II in the spindle 8 is adapted to removably connect the shell to the spindle.

The extreme inner end of the spindle 8 is in the form of a pilot l8 rotatable within a bushing l9 fitted in a bore 20' of a lower neck portion 2|, there being a disk 22 integral with the upper end of the neck 2| through which the bore 20 extends. The disk 22 is formed with opposed stops 23 and 24, the ends 01' which-provide shoulders 25 and 26 and 21 and 28 respectively.

The pilot portion l8 may be formed with a groove 29 into which balls 30 may be inserted through a threaded opening 3|. The opening 3| may be removably closed by a screwll. which will hold the balls in position and also permit lubrication when required.

On an intermediate portion of the spindle 6 is an eccentric 33, the lower face 34 or which contacts the disk 22. Said eccentric 33 is rotatable within a circular opening 35 of a clutch or driving member 36 having radial jaws 31 and 38. The said clutch member is held in proper position on the eccentric by an annular shoulder 33 at the outer end of the eccentric.

A coil spring 40 surrounds the spindle 8 below the shoulder I I and has one bent end 4| received in a longitudinal groove 42 of the spindle. The other end of the coil spring is hooked onto the pin 43' projecting from the upper face'of the clutch member 36.

Any tool such as the wrench head 44, shown in Fig. 1, may have its stem 45 inserted in an opening 46 in an extension 41 of the neck portion 2|. The tool may be removably locked in position by set screws 48, whereby the parts 2| and 22 form a tool holder.

In use of the device, when the spindle 8 is driven, the shell 15 will rotate therewith and due to the engagement between the jaw 31 and the shoulder 25 (see Fig. 3) the disk 22 and tool holder extension 41 will be rotated. During nor mal driving conditions the coil spring connection between the eccentric 33 and the clutch member 36 will cause driving of said clutch member. When resistance to turning is encoun tered as when a nut is almost or fully set, then the eccentric 33 will start to rotate within the opening 35 of the clutch member 36. This will cause movement of the wide portion A of the eccentric from the position of Fig. 3 to the position of. Fig. hand will causethe jaw 31 to be drawn radially inwardly along the-sh0u1der 25. v

as illustrated: in Fig. 4, and at the same time the spring is being wound up on the spindle. As the eccentric continues to rotate within the clutch member 36 to the position of Fi 5, the jaw 31 will ultimately be entirely disengaged from the shoulder 25. The tension stored in the coil spring will then throw the jaw 31 from the full line position of Fig. 5 to the dot-and-dash line position therein into engagement with the shoulder 28 of the stop 24. During such movement the weight of the jaw on the clutch member 36 will deliver a driving impact to the shoulder 28, giving the nut which is being tightened an additional turning movement. Following this impact the eccentric will act to disengage the jaw from the shoulder 28 and the jaw will ultimately be thrown back to the shoulder 25. When the nut or bolt is fully set, if the tool is still held in en-- gagement, the jaw will continue to snap around from the shoulder .25 to the shoulder 28.

II it is desired to operate the tool in a reverse direction the shell [5 is removed and the spring 46 is slipped ofi of the endof the spindle and replaced in a reverse position. The unit will then operate in the same manner as before described except that the jaw 38 will act in conjunction with the shoulders 21 and 26.

By the use of the radial jaw 31, when resistance is encountered and as the jaw is being drawn from the position 01'; Fig. 3 to the position of Figs. 4 and 5, the distance from the center to the driven point is being lessened, thus less strain is placed upon the driving motor than with devices embodying longitudinally movable clutch members wherein as the clutch members are being pulled apartafter resistance is being encountered the strain on the motor steadily stops to rotatably drive the tool holder, a driv-- increases. In addition, with the present invention it is unnecessary to have an eccentric with a long throw and, therefore, there is a minimum of binding torque and strain on the motor when the eccentric is rotating within the opening 36 of the clutch member. The construction also makes it possible to utilize a relatively lightweight spring because the weight of the thick jaw portion 31 of the clutch member 36, which part is sufficiently far removed from the center to provide substantial leverage, is utilized to deliver the driving impact.

It is apparent from the above that the construction is relatively simple and that it is well adapted either for use as an adaptor or for use as a permanent part of a power driven tool.

Various changes and modifications may be made without departing from the spirit of the invention, and all of such changes are contemplated as may come within the scope of the claims.

What I claim is:

i. In a power driven tool construction, a tool holder having a rotatable part formed with op positely disposed stops spaced radially outwardly from the axis of rotation, a driving member having a circular interior opening and having a jaw spaced radially outwardly from said' opening and normally engageable with one of said stops to rotatably drive the tool holder, a driving spindle having an eccentric thereon positioned in the opening of the driving member, a yielding connection between said spindle and driving member normally causing the driving mem-' ing of the driving member against the tension of said yielding connection when resistance is encountered to draw said jaw radially inwardly out of engagement with said stop, and said yielding means then acting to throw the jaw rotatably around the eccentric lnto engagement with the other stop with the weight of the jaw delivering a driving impact.

2. In a power driven tool construction, a tool holder having a rotatable part formed with oppositely disposed stops spaced radially outwardly from the axis of rotation, a driving member having a circular interior opening and having a jaw spaced radially outwardly from said opening and normally engageable with one of said ing spindle having an eccentric thereon positioned in the opening of the driving member,

a coil spring surrounding said spindle and hav-' ing one end connected thereto and having its other end connected to the driving member to normally cause the driving member to rotate with the spindle and drive the tool holder, said eccentric being rotatable in the opening of the a driving impact.

3. In a power driven tool construction, a tool holder having a rotatable part formed with stop means spaced radially outwardly from the axis of rotation, a rotatable driving member having a circular opening therein and normally having a driving engagement with said stop means releasable b'y inward radial movement of said mem- 2,256,490; her out of engagement with said stop means,

4. In a power driven tool construction. a tool holder having a rotatable Dart formed with stop means spaced radially outwardly from the axis of rotation, a rotatable driving member having v a circular opening therein andnormally having a driving engagement'with said stop means re-" leasable by inward radial movement of said member out of engagement with said stop means, means including an eccentric rotatable within said circular opening of said driving member for eifecting said inward radial movement when 1 said tool holder encounters apredetermined resistance to movement, and means for automatmeans after release.

ically re-engaging said member with said stop GIRARD c. ROBINSON. 

